Power conversion device

Abstract

To improve cooling performance of a power semiconductor device and a capacitor in a power conversion device and to reduce the size and the cost of the power conversion device.SOLUTION: A housing 4 includes a flow path 5 through which a refrigerant flows. A capacitor C includes a case 12 in which a fin 13 is formed. The capacitor C is disposed so as to position the fin 13 in the flow path 5. A power semiconductor 1 is disposed on the opposite side of the capacitor C with the flow path 5 therebetween. The power semiconductor 1 has a plane part 9 in which no cooling fin is formed. The power semiconductor 1 is disposed so as to bring the plane part 9 into contact with the refrigerant.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a cooling structure for power semiconductors and capacitors in a power conversion device. [Background technology]

[0002] FIG. 1 shows a circuit configuration of an inverter unit as an example of a general power conversion device, and FIG. 2 shows the configuration of a conventional inverter unit.

[0003] In the inverter unit 10, the capacitor C, which serves to smooth the DC link voltage, is a heat-generating component because a current always flows through the capacitor C. Therefore, the capacitor C needs to be cooled.

[0004] In the existing configuration, as shown in FIG. 2, cooling was achieved by placing a thermally conductive sheet 3 on the bottom surface (or, in some cases, the top surface) of the capacitor C so that it was in contact with the housing 4 of the inverter unit 10.

[0005] In addition, although the configuration in FIG. 2 shows that the flow path 5 is provided immediately below the condenser C, there are also configurations in which the flow path 5 is not provided immediately below the condenser C.

[0006] Similarly, the power semiconductor 1 is a heat generating component. The power semiconductor 1 is directly cooled by sealing the joint between the housing 4 and a base plate 7 provided with pin fins 6 etc. with a sealing member (O-ring) 8.

[0007] Incidentally, Patent Document 1 discloses a prior art in which a power semiconductor and a capacitor are arranged side-by-side in a liquid-cooling cooler as in FIG. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent Publication No. 2021-197838 [Patent Document 2] Patent Publication No. 2021-145477 Summary of the Invention [Problem to be solved by the invention]

[0009] However, the actual heat generating part of the capacitor C is inside the molded capacitor C (the capacitor element and the internal conductor). The heat generated inside the capacitor C is dissipated via the resin mold → the case of the capacitor C → the thermally conductive sheet 3 → the housing 4 of the inverter unit 10 → the flow path 5, so sufficient cooling performance cannot be obtained.

[0010] The downsizing and heat generation of each item are issues in realizing a compact inverter unit 10 (high output density). The capacitor C and the power semiconductor 1 are large components even within the inverter unit 10 (they tend to be the largest in volume among the electrical components shown in the electrical circuit of FIG. 1), and so the heat generated by these components has been a bottleneck.

[0011] In view of the above, it is necessary to improve the cooling capacity of the power semiconductor elements and the capacitor in a power conversion device, and to reduce the size and cost of the power conversion device. [Means for solving the problem]

[0012] The present invention was devised in consideration of the above-mentioned problems in the conventional technology, and one aspect of the present invention is characterized by comprising: a housing having a flow path through which a refrigerant flows, a capacitor having a case on which fins are formed, and arranged so that the fins are located within the flow path, and a power semiconductor that is arranged on the opposite side of the capacitor across the flow path, has a flat portion on which no cooling fins are formed, and is arranged so that the flat portion is in contact with the refrigerant.

[0013] In one aspect, the power semiconductor has a base plate on which the flat portion is formed, and is arranged so that the flat portion of the base plate is in contact with the coolant.

[0014] In another aspect, the power semiconductor is in the shape of a power card on which the flat surface is formed, and the flat surface of the power card is disposed so as to be in contact with the refrigerant.

[0015] In one aspect, a seal member is provided at least on either or both of a joint between the capacitor and the housing and a joint between the planar portion of the power semiconductor and the housing.

[0016] In another aspect, at least one or both of the joint between the capacitor and the housing and the joint between the planar portion of the power semiconductor and the housing are joined by thermal welding. Effect of the Invention

[0017] According to the present invention, in a power conversion device, it is possible to improve the cooling capacity of a power semiconductor element and a capacitor, and to reduce the size and cost of the power conversion device. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a diagram showing a circuit configuration of a general power conversion device. [Diagram 2] FIG. 1 is a cross-sectional view showing the configuration of a conventional power conversion device. [Diagram 3] 1 is a cross-sectional view showing a configuration of a power conversion device according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of a power conversion device according to the present invention will be described in detail with reference to Figs.

[0020] [Embodiment] First, a typical power conversion device (for example, an inverter unit, hereinafter referred to as the inverter unit) will be described based on the electric circuit diagram in Fig. 1. As shown in Fig. 1, a capacitor (for example, a film capacitor) C is connected between a P terminal and an N terminal. In addition, switching elements Su, Sx, switching elements Sv, Sy, and switching elements Sw, Sz are connected in series between the P terminal and the N terminal. The switching elements are, for example, IGBTs, and the switching elements Su to Sz constitute a power semiconductor (IGBT package) 1.

[0021] A motor M is connected to the AC side (the connection point of the switching elements Su and Sx, the connection point of the switching elements Sv and Sy, and the connection point of the switching elements Sw and Sz) of the power semiconductor 1. In addition, a current sensor 2 is provided between the power semiconductor 1 and the motor M.

[0022] Capacitor C serves to smooth the DC link voltage. A discharge resistor R is connected in parallel to capacitor C. Discharge resistor R is provided to discharge the charge in capacitor C when the input power of inverter unit 10 is turned off. This prevents electric shock accidents.

[0023] The configuration of the inverter unit 10a in this embodiment is shown in FIG.

[0024] In this embodiment, a capacitor C with fins 13 is arranged on one surface of the flow path 5, and a power semiconductor 1 having a flat portion 9 on which no cooling fins are formed is arranged on the other surface of the flow path 5. With this configuration, both the power semiconductor 1 and the capacitor C, which are heat generating bodies in the inverter unit 10a, are cooled. The configuration of the inverter unit 10a of this embodiment will be described in detail below.

[0025] A flow path 5 through which a coolant (for example, water) flows is formed in a housing 4 (for example, a water channel case) of the inverter unit 10a.

[0026] Condenser C includes case 12 and fins 13 extending from case 12. Fins 13 are disposed within flow path 5. By disposing fins 13, the cooling area (the area where case 12 and fins 13 are in contact with the refrigerant) can be increased, and the cooling capacity can be improved.

[0027] The power semiconductor 1 is disposed on the opposite side of the capacitor C across the housing 4 (flow path 5). The power semiconductor 1 includes a case 11 made of resin and a base plate 7 made of metal. The base plate 7 has a flat portion 9 on which no cooling fins are formed, and is disposed so that this flat portion 9 comes into contact with the refrigerant in the flow path 5. The case 11 and the base plate 7 are joined together with screws or the like.

[0028] In this manner, a sandwich configuration is formed in which the flow path 5 (housing 4) is sandwiched between the capacitor C having the fins 13 formed on the case 12 and the power semiconductor 1 whose cooling surface is the flat portion 9 of the base plate 7.

[0029] A seal member (O-ring or the like) 8 is provided at the joint between the capacitor C and the housing 4 and at the joint between the power semiconductor 1 and the housing 4. The seal member 8 is used to bring the capacitor C and the housing 4 and the power semiconductor 1 and the housing 4 into close contact with each other, thereby ensuring watertightness. Instead of the seal member 8, the joint between the capacitor C and the housing 4 and the joint between the power semiconductor 1 and the housing 4 may be joined by thermal welding. With this configuration, the capacitor C and the power semiconductor 1 are directly cooled by the flow path 5 (coolant). The seal member 8 may be provided at at least one of the joint between the capacitor C and the housing 4 and the joint between the power semiconductor 1 and the housing 4, or at least one of the joint between the capacitor C and the housing 4 and the joint between the power semiconductor 1 and the housing 4 may be joined by thermal welding.

[0030] The material of case 12 of capacitor C is generally a resin material such as PPS (Polyphenylenesulfide), but other metals such as aluminum having high thermal conductivity may also be used.

[0031] The shape of the fins 13 of the condenser C may be, for example, a round pin shape, a diamond shape, or a comb shape (including cutting and extrusion), but the shape is not limited to these and may be any shape that can generate turbulence.

[0032] A high cooling effect can be obtained by forming fins 13 on the case 12 of the capacitor C and directly cooling it through the flow path 5. That is, in the past, the generated heat was dissipated via the resin mold → the case of the capacitor C → the thermally conductive sheet → the housing of the inverter unit → the flow path, but in this embodiment, the generated heat is dissipated via the resin mold → the case 12 (fins 13) of the capacitor C → the flow path 5. In this way, the heat dissipation path is shortened, and therefore the cooling effect of the capacitor C can be improved.

[0033] Furthermore, the fins 13 of the case 12 of the capacitor C generate turbulence in the flow path 5 immediately adjacent to the base plate 7 of the power semiconductor 1. This turbulence can also enhance the cooling effect of the power semiconductor 1.

[0034] This eliminates the need to provide cooling fins on the base plate 7 of the power semiconductor 1, improving the degree of freedom in packaging the power semiconductor 1. Note that, although the power semiconductor 1 is a flat-based flat module as an example, it is also possible to apply a power card shape having a flat surface.

[0035] According to this embodiment, the condenser C directly cools the fins 13 through the flow path 5, and the heat dissipation path is shortened, improving the cooling capacity. In addition, the increase in the cooling area provided by the fins 13 also improves the cooling capacity of the condenser C.

[0036] Furthermore, fins 13 of capacitor C generate turbulence in flow path 5, thereby improving the cooling effect of power semiconductor 1.

[0037] Furthermore, the turbulent flow in the flow path 5 improves the cooling capacity of the power semiconductor 1, eliminating the need to provide cooling fins on the power semiconductor 1, and therefore the cooling surface of the base plate 7 of the power semiconductor 1 can be made flat (the flat surface portion 9 can be formed). Since the cooling surface of the base plate 7 can be made flat (the flat surface portion 9 can be formed), design freedom can be improved. In other words, the shape of the cooling surface of the power semiconductor 1 can be simplified, and the freedom of the package shape of the power semiconductor 1 is improved.

[0038] The increased freedom in designing the power semiconductor 1 allows the inverter unit 10a to have a higher output density (smaller size) and lower costs.

[0039] Also, when assembling the inverter unit 10a, it is possible to eliminate the need for a thermally conductive sheet to be attached to the capacitor C. Furthermore, it is possible to eliminate the step of attaching the thermally conductive sheet.

[0040] Although the present invention has been described in detail above only with respect to the specific examples, it will be apparent to those skilled in the art that various modifications and variations are possible within the scope of the technical concept of the present invention, and it is natural that such modifications and variations fall within the scope of the claims. [Explanation of symbols]

[0041] C: Capacitor M: Motor Su~Sz...Switching elements 1...Power semiconductor (IGBT package) 2...Current sensor 3…Heat conductive sheet 4. Housing 5...Flow path 6. Pinfin 7…Base blade 8...Sealing material (O-ring) 9…Plane part 10, 10a...Power conversion device (inverter unit) 11…Power semiconductor case 12...Capacitor case 13. Finn

Claims

1. a housing having a flow path through which a coolant flows; a capacitor having a case on which fins are formed, the fins being disposed within the flow path; a power semiconductor disposed on the opposite side of the capacitor with the flow path interposed therebetween, the power semiconductor having a flat portion on which no cooling fins are formed, the flat portion being disposed so as to be in contact with the refrigerant; A power conversion device comprising:

2. 2. The power conversion device according to claim 1, wherein the power semiconductor has a base plate on which the flat portion is formed, and the flat portion of the base plate is disposed so as to be in contact with the coolant.

3. 2. The power conversion device according to claim 1, wherein the power semiconductor is in the form of a power card on which the flat surface is formed, and the flat surface of the power card is disposed so as to be in contact with the refrigerant.

4. 2. The power conversion device according to claim 1, further comprising a seal member provided at least on either or both of a joint between the capacitor and the housing and a joint between the planar portion of the power semiconductor and the housing.

5. 2. The power conversion device according to claim 1, wherein at least one or both of a joint between the capacitor and the housing and a joint between the planar portion of the power semiconductor and the housing are joined by thermal welding.

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